Conan, now a member of an Aesir war party, is just finishing off a band of Vanir in the snowy plains, but soon stumbles and falls due to his injuries. A beautiful, scantily clad maiden appears to him, and when she tempts him a little too much, he chases her lustily towards the mountains, knowing she might be luring him to an ambush. When her frost giant brothers appear, he swiftly deals with them and continues his chase, finally catching her. She prays to her father, the god Ymir, to save her, and she vanishes in a flash of blue light. Conan collapses, and is rescued by his Aesir companions, who, while they don't entirely believe his story, are disquieted with the remnants of a dress Conan holds in his hand.

Dr. Theodore "Ted" Sallis is a scientist working on a variation of the lost super-soldier serum on behalf of a government contractor. He sets up shop in the Florida Everglades with his assistant (and lover), Ellen Brandt. What he doesn't realize though, is that Brandt is actually a spy working for a criminal organization. As soon as Sallis confirms the success of his super-soldier serum, Brandt contacts her people.

The thugs raid Sallis' lab and try to steal the formula from him. The only existing sample is contained within a needle. Ted grabs the sample and races out towards his car. The thugs begin following him. Driving away, Sallis realizes that the only way that he might survive (and preserve the formula) is to inject himself with it. If nothing else, he succeeds in keeping it out of criminal hands.

After injecting himself with the formula, Ted's car goes off a bridge and into the swamp. The super-soldier serum coursing through his bloodstream interfaces with the surrounding vegetation and transforms Sallis into a mindless, shambling muck-monster that men will come to call the Man-Thing!

The Man-Thing rises from the swamp and attacks the criminals. He grabs one and shatters his spine against his knee. Ellen Brandt is present and begins screaming. The Man-Thing discovers that he has an empathic connection to all humans, and fear produces a swelling of rage within him. He grabs Ellen by the face and secretes a corrosive substance from his pores, burning Ellen badly. Whatever knows fear... burns at the touch of the Man-Thing!

A couple Carla and Ralph come to the Savage Land with a Swamp Tank to steal Ka-Zar's vibranium, but when they force him to open the door to where it is stored the vibranium destroys the tank. Carla is carried off and killed by the Swamp Men when Ralph is not able to save her because the gun he was using only had blanks due to Carla replacing the bullets with blanks in an effort to get Ralph killed.

The original version of "The Frost Giant's Daughter", authored by Robert E. Howard, was never published in Howard's lifetime. Howard submitted the story to Weird Tales under the name "The Frost King's Daughter", but then-editor Farnsworth Wright rejected it. Instead, Weird Tales published "The Phoenix on the Sword", a provincial story that launched the entire Conan franchise. Although the story had gone through numerous revisions over the years, it was eventually published in 1976 in Donald Grant's deluxe hardcover collection of Conan stories.